goweb

README

GoWeb

A simple HTTP responder, written in Go.

File goweb.go contains the code that is to be compiled and run by means of containers.
The source code describes two functions:

1. main(): listens and servers any HTTP GET requests on port 8888 (listenPort)
2. sayHello(): returns a message saying This is <hostname> running on <OS/arch> saying: <received_message>

Local test

Run as go run goweb.go. From a different terminal tab, run the following:

$ curl http://127.0.0.1:8888/Hello%20GoWeb\!
This is <hostname> running on linux/amd64 saying: Hello GoWeb!

---

Build and run as container

• build

$ docker buildx build --tag <repository>/<name>:<tag> .

NOTE: mind the dot (".") at the end of the command above

• run

$ docker run \
  --detach \
  --publish published=8080,target=8888 \
  --name responder \
  <repository>/<name>:<tag>

• test

$ curl http://<private_subnet_ip_address>:8080/Hello%20GoWeb\!
This is <hostname> running on linux/amd64 saying: Hello GoWeb!

NOTE: the published port (8080) is different from the listening port (8888)

Run with Docker Swarm

• run

$ docker service create \
  --replicas 3 \
  --name responder \
  --publish published=8080,target=8888 \
  <repository>/<name>:<tag>

• test

$ curl http://<private_subnet_ip_address>:8080/Hello%20GoWeb\!
This is <hostname> running on linux/amd64 saying: Hello GoWeb!

To scale up/down

$ docker service scale goweb=5

NOTE: the numbers 3 and 5 above are only examples

---

Run as a Stack

$ docker stack deploy \
  --compose-file compose.yaml
 responder 

NOTE: what was before stated through the command line is now described in the compose.yaml file

---

Add a load balancer (nginx)

Take a look and edit as appropriate file data/loadbalancer/default.conf.ori. The file defines:

• backend: the servers (private subnet IP addresses) and ports on which the service stack is offered

• listen: the port on which the LB operates (within the container)
  

• run

docker run \
  --detach \
  --name loadbalancer \
  --mount type=bind,source=./data/loadbalancer,target=/etc/nginx/conf.d \
  --publish published=9090,target=9999 \
  nginx

• test

$ curl http://<private_subnet_ip_address>:9090/Hello%20GoWeb\!
This is <hostname> running on linux/amd64 saying: Hello GoWeb!

---

See also: https://www.digitalocean.com/community/tutorials/how-to-make-an-http-server-in-go